1. Field of the Invention
The present invention relates to a liquid crystal display(LCD) module, and more particularly, to a modified LCD module using a plurality of light emitting diodes (LEDs) as a backlight source.
2. Description of the Prior Art
Liquid crystal display (LCD) devices have been widely used in notebooks, personal digital assistants(PDAs), cellular phones, and other electronic products because the price of LCDs is low and the quality of LCDs is high. LCDs are passive optical devices. Therefore, a frontlight module or a backlight module needs to be attached to the LCD panel to provide sufficient illumination to make the LCD device visible at night and display in full color. Generally, the backlight module, comprising a light source generation and a diffusion sheet, is usually attached below the LCD panel to provide the light source and to disperse the light uniformly. The dispersed light is imported to the LCD panel to display an image.
Currently, the light source generator of the backlight module usually is one of two types. One type is a cold cathode fluorescence lamp (CCFL) and the other type is a light emitting diode (LED). The luminescent efficiency of the CCFL is relatively higher, but the volume of the CCFL is bigger and the CCFL consumes more electricity. Therefore, the CCFL is only suitable for a multicolored display having great brightness levels and a big size. The luminescent efficiency of the LED is lower, the volume of the LED is smaller, the emitter light of the LED is more focused, and the life of the LED is longer. In addition, even when the LED is abandoned, the LED results in less pollution. Therefore, the LED is suitable for a monochromatic, electrically-efficient small sized product, such as an LCD panel used in a cellular phone or used in a vehicles satellite navigation system.
Please refer to FIG. 1, which is a structural schematic diagram of an LCD module 10 according to the prior art. As shown in FIG. 1, the LCD module 10 comprises an LCD panel 12 used for displaying an image, a backlight module 14 used for providing a light source, a printed circuit board (PCB) 16, a flexible printed circuit board (FPCB) 18 used to electrically connect the LCD panel 12 with the PCB 16, and a FPCB 20 used to electrically connect the backlight module 14 with the PCB 16.
Generally, the backlight module 14 comprises a plurality of LEDs arranged in an array and formed on a substrate. A reflecting plate, a light-guide plate, a diffusion sheet, and an optical prism are installed on the substrate of the backlight module 14 (not shown). The light-guide plate keeps the light produced by the LEDs illuminating the LCD panel 12 more uniformly. The reflecting plate mostly adheres to the lower surface of the light-guide plate for reflecting the light produced by the LEDs upward to increase the light utilization rate. The reflecting plate could be a smooth white cardboard. The diffusion sheet diffuses the incident light source to provide a more uniform light source to the LCD panel. The optical prism increases the light intensity. Additionally, the quantities and the arrangement of the reflecting plate, the light-guide plate, the diffusion sheet, and the optical prism could be modified according to design requirements.
It is noted that the PCB 16 further comprises a plurality of electrical components (not shown). The LCD panel 12 further comprises at least one source driver integrated circuit 22 and at least one drain driver integrated circuit 24. The FPCB 18 electrically connects the electrical components of the PCB 16 with the source driver integrated circuit 22 and the driver integrated circuit 24 of the LCD panel 12. The FPCB 18 also electrically connects with the LEDs of the backlight module 14. Therefore, the LCD module 10 of the prior art can control the electrical components of the PCB 16 to make the LEDs illuminate, and to drive the source driver integrated circuit 22 and the driver integrated circuit 24 of the LCD panel 12 to illuminate the LCD panel 12 to display an image.
Furthermore, the LCD module 10 also can mount the FPCB 20, electrically connecting with the backlight module 14, by a way that is to adhere or to solder or to electrically connect with the FPCB 18. Additionally, the FPCB 18 electrically connects with the PCB 16.
However, the aforementioned LCD modules 10 of the prior art need the FPCB 18 and the FPCB 20 to respectively electrically connect the LCD panel 12, the backlight module 14, and the PCB 16 to respectively drive the LCD panel 12 and the backlight module 14. However, the price of the FPCB is very expensive. Therefore, how to compete in the market, how to reduce the cost, and how to fabricate a product with a high quality are big problems in the current LCD module field.